559 research outputs found
Effect of external PEEP in patients under controlled mechanical ventilation with an auto-PEEP of 5 cmH2O or higher.
In some patients with auto-positive end-expiratory pressure (auto-PEEP), application of PEEP lower than auto-PEEP maintains a constant total PEEP, therefore reducing the inspiratory threshold load without detrimental cardiovascular or respiratory effects. We refer to these patients as complete PEEP-absorbers. Conversely, adverse effects of PEEP application could occur in patients with auto-PEEP when the total PEEP rises as a consequence. From a pathophysiological perspective, all subjects with flow limitation are expected to be complete PEEP-absorbers, whereas PEEP should increase total PEEP in all other patients. This study aimed to empirically assess the extent to which flow limitation alone explains a complete PEEP-absorber behavior (i.e., absence of further hyperinflation with PEEP), and to identify other factors associated with it.One hundred patients with auto-PEEP of at least 5 cmH2O at zero end-expiratory pressure (ZEEP) during controlled mechanical ventilation were enrolled. Total PEEP (i.e., end-expiratory plateau pressure) was measured both at ZEEP and after applied PEEP equal to 80 % of auto-PEEP measured at ZEEP. All measurements were repeated three times, and the average value was used for analysis.Forty-seven percent of the patients suffered from chronic pulmonary disease and 52 % from acute pulmonary disease; 61 % showed flow limitation at ZEEP, assessed by manual compression of the abdomen. The mean total PEEP was 7 ± 2 cmH2O at ZEEP and 9 ± 2 cmH2O after the application of PEEP (p < 0.001). Thirty-three percent of the patients were complete PEEP-absorbers. Multiple logistic regression was used to predict the behavior of complete PEEP-absorber. The best model included a respiratory rate lower than 20 breaths/min and the presence of flow limitation. The predictive ability of the model was excellent, with an overoptimism-corrected area under the receiver operating characteristics curve of 0.89 (95 % CI 0.80-0.97).Expiratory flow limitation was associated with both high and complete PEEP-absorber behavior, but setting a relatively high respiratory rate on the ventilator can prevent from observing complete PEEP-absorption. Therefore, the effect of PEEP application in patients with auto-PEEP can be accurately predicted at the bedside by measuring the respiratory rate and observing the flow-volume loop during manual compression of the abdomen
The Messinian salinity crisis: open problems and possible implications for Mediterranean petroleum systems
Abstract: A general agreement on what actually happened during the Messinian salinity crisis (MSC) has been reached in the
minds of most geologists but, in the deepest settings of the Mediterranean Basin, the picture is still far from being finalized and
several different scenarios for the crisis have been proposed, with different significant implications for hydrocarbon
exploration. The currently accepted MSC paradigm of the ‘shallow-water deep-basin’ model, which implies high-amplitude
sea-level oscillations (> 1500 m) of the Mediterranean up to its desiccation, is usually considered as fact. As a consequence, it is
on this model that the implications of the MSC events on the Mediterranean petroleum systems are commonly based.
In fact, an alternative, deep-water, non-desiccated scenario of the MSC is possible: it (i) implies the permanence of a large
water body in the Mediterranean throughout the entire Messinian salinity crisis, but with strongly reduced Atlantic connections;
and (ii) envisages a genetic link between Messinian erosion of the Mediterranean margins and deep brine development.
In this work, we focus on the strong implications of an assessment of the petroleum systems of the Mediterranean and
adjoining areas (e.g. the Black Sea Basin) that can be based on such a non-desiccated MSC scenario. In particular, the near-full
basin model delivers a more realistic definition of Messinian source-rock generation and distribution, as well as of the
magnitude of water-unloading processes and their effects on hydrocarbon accumulation
Geophilomorph centipedes (Chilopoda) from termite mounds in the northern Pantanal wetland of Mato Grosso, Brazil
Of two species of geophilomorph centipedes collected above high waters in termite mounds in the Pantanal of Mato Grosso, one (Schendylops inquilinus) is described here as new; the other (Aphilodon angustatus Silvestri, 1909) is redescribed.Facultad de Ciencias Naturales y Muse
Emergency Plasmapheresis in a case of ThromboticThrombocytopenic Purpura (TTP)
An 84 year-old female was admitted to our Department of Vascular Internal Medicine after a sudden onset of weakness on her right side and aphasia along with signs of myocardial ischemia from Electrocardiogram (EKG). Clinical and blood exams led to a suspicion of Moschcowitz syndrome, which was reinforced by the presence of numerous schistocytes on a peripheral blood smear.Due to a rapid deterioration of vital signs as well as alertness, the patient underwent an emergency transfusion and plasmapheresis treatment as recommended by American Society of Apheresis (ASFA) guidelines: one plasma volume was replaced with fresh frozen plasma (FFP) every 24 hours, for the first eight days, in order to reach at least a level of 150,000 platelets/mm3 over three consecutive days accompanied by a decrease in LDH until to 670 UI/l.After this therapy, the clinical picture significantly improved with a complete recovery of consciousness and the disappearance of neurological defects.Examinations to determine the etiology made us hypothesize a secondary status of thrombotic thrombocytopenic purpura due to an autoimmune disorder compatible with Sjogren’s syndrome. The patient was discharged and prescribed prednisone.Currently the patient is in good clinical condition and continues the therapy with prednisone (5 mg/die)
Study on ammonia transport and separation in Aquivion® perfluoro sulfonated acid membranes
The present study reports the results of a series of sorption and permeation tests of pure ammonia as well as
nitrogen and hydrogen carried out on Aquivion C87-05 (short-side chain perfluoro sulfonic acid ionomer). Such
material is indeed of interest for possible applications in sustainable processes for ammonia production, either as
base material for polymer electrolyte membranes in low-temperature electrochemical ammonia synthesis or as a
membrane for effective product separation.
NH3, N2, and H2 permeation tests are performed at different temperatures (20, 35, and 50 ◦C) and both in dry
and humid conditions (R.H. up to 80%), aiming to assess the influence of these parameters on the resulting
permeabilities, while ammonia sorption is inspected at the same temperatures, and pressures up to near saturation conditions.
Pure ammonia permeability reached outstanding values around 7000 Barrer in dry Aquivion membranes,
revealing an increasing trend with upstream pressure, while it decreased with temperature. The same behavior is
recorded for NH3 solubility, indicating that sorption drives the ammonia transport through the membrane.
The obtained separation performances are found to be significantly better than those of other polymeric
membranes proposed for the same separations, as compared to a permeability-selectivity plot
The species of Schendylops Cook, 1899 (Chilopoda, Geophilomorpha, Schendylidae) from Madagascar
Four of the five species of the geophilomorph centipede genus Schendylops Cook, 1899 hitherto known from Madagascar, i.e. S. insolitus (Lawrence, 1960), S. paucispina (Lawrence, 1960), S. mascarenicus (Lawrence, 1960) and S. silvicola (Lawrence, 1960), are re-described based on the type material preserved in the collections of the Muséum national d’Histoire naturelle in Paris. A key is provided for the identification of all Malagasy species of the genus, which likely form a clade within Schendylops.Quatre espèces de chilopodes géophilomorphes du genre Schendylops Cook, 1899 parmi les cinq connues jusqu’ici de Madagascar, c’est-à-dire S. insolitus (Lawrence, 1960), S. paucispina (Lawrence, 1960), S. mascarenicus (Lawrence, 1960) et S. silvicola (Lawrence, 1960), sont redécrites d’après le matériel type conservé dans les collections du Muséum national d’Histoire naturelle de Paris. Une clé est fournie pour l’identification de toutes les espèces de ce genre connues de Madagascar, qui forment très vraisemblablement un clade.Facultad de Ciencias Naturales y Muse
A New Method for Hybrid Bermuda Grass (Cynodon dactylon × C. transvaalensis Burtt.-Davy) Vegetative Propagation
Hybrid Bermuda grasses (Cynodon dactylon × C. transvaalensis Burtt.-Davy) represent one of the greatest contributions to the growing quality of turfgrass in the warm season and transition zone areas of the world. Hybrid Bermuda grass production relies on vegetative propagation from sod or sprigs. In the past, efforts have focused on improving the technique of stolonizing (or sprigging) for establishment in new areas. Such propagation requires bulk harvesting and planting of all rhizomes and stolons. We have developed a novel method of propagation and establishment from a single node harvested from greenhouse grown stolons. Despite a stolon fraction bearing a single node being suitable for effectively propagating a warm-season turfgrass, the technique has been held as economically impractical until now. Our method has been developed to obtain the multiplication of plant material in soilless conditions by harvesting single-node sprigs, propagation of plants from the single nodes, and transplant of single plants in the field. The investigation aimed to identify values for method set-up. Indeed, node and internode size variability with differential between maximum diameters is crucial for discrimination. For Patriot Bermuda grass stolons, nodes exhibited a maximum diameter of 2.43 ± 0.46 mm, while internodes had a maximum diameter of 1.54 ± 0.16 mm. Based on these findings, a 2 mm sieve was selected, achieving an optimal ratio between the node fraction and internode residues. The sieve yielded 87% of node fractions and only 1% of internodes from the initial mix, demonstrating its efficacy. Further results for the transplanting phase indicated that a double release resulted in an average success rate of 98.8%, with only 6.9% blank cells when using a single release. The average was 149 plants per tray over 160 cells, representing a 93.1% success rate. These results underscore the efficiency and acceptability of the overall propagation process in alignment with market references
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